Secondary channel estimation

Abstract

Some example embodiments may be directed towards improving a secondary system channel estimation by using a primary channel estimate. Specifically, some example embodiments may be directed towards a method in an user equipment, which may be comprised in a Radio Network, for estimating a primary and a secondary channel. The method may comprise receiving from at least one Base Station a combined wireless communication signal through at least a portion of the primary channel. The method may also comprise determining an estimation of the primary channel. The method may further comprise determining an estimation of the secondary channel. The method may further comprise determining at least one common sub-component between the estimations of the primary and secondary channels, and determining an updated estimation of the secondary channel based on the at least one common sub-component.

The invention claimed is: 
     
       1. A method in a user equipment comprising:
 receiving a primary signal from one or more transmitters, including receiving the primary signal from at least one of said transmitters as a combined wireless communication signal that further includes a secondary signal; 
 determining a primary channel estimate based on pilot resources in the primary signal, as received from the one or more transmitters transmitting the primary signal; 
 determining a secondary channel estimate based on pilot resources in the secondary signal, as received from the at least one transmitter transmitting the combined wireless communication signal; 
 identifying a portion of the primary channel estimate that corresponds with the secondary channel estimate, said portion stemming from receipt of the primary signal in the combined signal; and 
 updating the secondary channel estimate using the identified portion of the primary channel estimate. 
 
     
     
       2. The method of  claim 1 , wherein determining the primary channel estimate further comprises:
 reconstructing the primary signal as received in the combined wireless communication signal; and 
 re-estimating the primary channel using the reconstructed primary signal as a pilot resource. 
 
     
     
       3. The method of  claim 1 , wherein identifying the portion of the primary channel estimate that corresponds with the secondary channel estimate comprises determining at least one common sub-component by:
 constructing first and second time domain representations of the primary and secondary channels, respectively; 
 comparing the first and second time domain representation; and 
 determining at least one period of time wherein the first and second time domain representation are similar, based on the comparing. 
 
     
     
       4. The method of  claim 1 , wherein identifying the portion of the primary channel estimate that corresponds with the secondary channel estimate comprises determining at least one common sub-component by:
 constructing first and second frequency domain representations of the primary and secondary channels, respectively; 
 comparing the first and second frequency domain representations; and 
 determining at least one similar complex exponential waveform of the first and second frequency domain representations, based on the comparing. 
 
     
     
       5. The method of  claim 1 , wherein updating the secondary channel estimate comprises assigning the identified portion of the primary channel estimate as the secondary channel estimate, if time or frequency domain representations of the identified portion of the primary channel estimate and the secondary channel estimate are the same. 
     
     
       6. The method of  claim 1 , wherein determining the primary channel estimate further comprises sending information to a network node associated with transmission of the combined wireless communication signal, said information providing an indication to maximize a pilot resource overlap between the primary and secondary signals. 
     
     
       7. The method of  claim 1 , wherein determining the secondary channel estimate further comprises sending information to a network node associated with transmission of the combined wireless communication signal, said information providing an indication to minimize a pilot resource overlap between the primary and secondary signals. 
     
     
       8. The method of  claim 1 , wherein the primary signal comprises broadcast communication signals. 
     
     
       9. The method of  claim 1 , wherein the secondary signal comprises broadband communication signals. 
     
     
       10. The method of  claim 1 , wherein identifying the portion of the primary channel estimate that corresponds with the secondary channel estimate comprises determining taps in the primary channel estimate that are common with taps in the secondary channel estimate. 
     
     
       11. The method of  claim 10 , wherein updating the secondary channel estimate comprises replacing or revising the secondary channel estimate with values from the primary channel estimate for the common taps. 
     
     
       12. The method of  claim 1 , wherein the at least one transmitter operates in an overlay communication system utilizing spectrum sharing as between the primary and secondary signals, and wherein the at least one transmitter transmits the combined wireless communications signal according to a predetermined pattern of primary and secondary signal transmissions, and wherein the method further includes:
 receiving control signaling indicating the predetermined pattern; and 
 performing primary and secondary channel estimation according to the predetermined pattern. 
 
     
     
       13. A method in a user equipment configured for operation in an overlay communication system that utilizes spectrum sharing between a primary signal associated with a primary system and a secondary signal associated with a secondary system, said method comprising:
 receiving the secondary signal from a first transmitter operating in the overlay communication system; 
 receiving the primary signal from two or more transmitters operating in the overlay communication system, said two or more transmitters including the first transmitter, such that a secondary channel associated with transmission of the secondary signal from the first transmitter is a subset of an overall primary channel associated with transmission of the primary signal from the two or more transmitters; 
 determining a secondary channel estimate for the secondary channel, based on reception of the secondary signal from the first transmitter; 
 determining a primary channel estimate for the overall primary channel, based on reception of the primary signal from the two or more transmitters; 
 identifying that portion of the primary channel estimate that stems from transmission of the primary signal from the first transmitter; and 
 updating the secondary channel estimate based on the identified portion of the primary channel estimate. 
 
     
     
       14. A user equipment comprising:
 a communications port configured to receive a primary signal from one or more transmitters, including receiving the primary signal from at least one of said transmitters as a combined wireless communication signal that further includes a secondary signal; 
 an estimation unit configured to determine a primary channel estimate based on pilot resources in the primary signal, as received from the one or more transmitters transmitting the primary signal, and to determine a secondary channel estimate based on pilot resources in the secondary signal, as received from the at least one transmitter transmitting the combined wireless communication signal; 
 an evaluation unit configured to identify a portion of the primary channel estimate that corresponds with the secondary channel estimate, said portion stemming from receipt of the primary signal in the combined wireless communication signal; and 
 wherein the estimation unit is further configured to update the secondary channel estimate using the identified portion of the primary channel estimate. 
 
     
     
       15. The user equipment of  claim 14 , wherein the evaluation unit is configured to identify the portion of the primary channel estimate that corresponds with the secondary channel estimate by determining taps in the primary channel estimate that are common with taps in the secondary channel estimate. 
     
     
       16. The user equipment of  claim 15 , wherein the evaluation unit is configured to update the secondary channel estimate by replacing or revising the secondary channel estimate with values from the primary channel estimate for the common taps. 
     
     
       17. The user equipment of  claim 14 , wherein the at least one transmitter operates in an overlay communication system utilizing spectrum sharing as between the primary and secondary signals, and transmits the combined wireless communications signal according to a predetermined pattern of primary and secondary signal transmissions, and wherein the estimation unit is further configured to:
 receive, via the communications port, control signaling indicating the predetermined pattern; and 
 perform primary and secondary channel estimation according to the predetermined pattern. 
 
     
     
       18. The user equipment of  claim 14 , wherein the primary signal comprises broadcast communication signals. 
     
     
       19. The user equipment of  claim 14 , wherein the secondary signal comprises broadband communication signals.